Thread: Build error: math library not linked
after trying my luck with lighthouseapp, let me post the bug here: I upgraded to mageia α2, which uses python2.7 . Trying to build psycopg2 again for it, stumbled accross unresolved errors for the floating point functions. Indeed, final linking step didn't include "-lm" to the linker. Added it with commit 4e29da5cda6aa3, as found at: http://members.hellug.gr/xrg/repos/psycopg2 (browse at http://git.hellug.gr/?p=xrg/psycopg2) Please check your platforms. Is libm already linked against? Could you forecast any side-effect from explicitly mentioning it (as in the patch) ? -- Say NO to spam and viruses. Stop using Microsoft Windows!
On 13/03/11 23:21, P. Christeas wrote: > I upgraded to mageia α2, which uses python2.7 . Trying to build psycopg2 again > for it, stumbled accross unresolved errors for the floating point functions. > Indeed, final linking step didn't include "-lm" to the linker. > > Added it with commit 4e29da5cda6aa3, as found at: > http://members.hellug.gr/xrg/repos/psycopg2 > (browse at http://git.hellug.gr/?p=xrg/psycopg2) > > Please check your platforms. Is libm already linked against? Could you > forecast any side-effect from explicitly mentioning it (as in the patch) ? On my Linux box libm is not linked in and I don't have any problem. Can you please tell us you system version and the exact errors? federico -- Federico Di Gregorio federico.digregorio@dndg.it Studio Associato Di Nunzio e Di Gregorio http://dndg.it Una nazionale senza neanche una nazione. -- macchinavapore
On Monday 14 March 2011, Federico Di Gregorio wrote: > On 13/03/11 23:21, P. Christeas wrote: > > I upgraded to mageia α2, which uses python2.7 . Trying to build psycopg2 > > again for it, stumbled accross unresolved errors for the floating point > > functions. Indeed, final linking step didn't include "-lm" to the > > linker. > > > > Added it with commit 4e29da5cda6aa3, as found at: > > http://members.hellug.gr/xrg/repos/psycopg2 > > (browse at http://git.hellug.gr/?p=xrg/psycopg2) > > > > Please check your platforms. Is libm already linked against? Could you > > forecast any side-effect from explicitly mentioning it (as in the patch) > > ? > > On my Linux box libm is not linked in and I don't have any problem. Can > you please tell us you system version and the exact errors? > > federico Do you use -Wl,no-undefined at the linker? My problem is at that step, and I highly suspect that if I hadn't had that, the binary (psycopg.so) would still run against the python binary (because python will load libm anyway). -- Say NO to spam and viruses. Stop using Microsoft Windows!
On 14/03/11 13:59, P. Christeas wrote: > On Monday 14 March 2011, Federico Di Gregorio wrote: >> > On 13/03/11 23:21, P. Christeas wrote: >>> > > I upgraded to mageia α2, which uses python2.7 . Trying to build psycopg2 >>> > > again for it, stumbled accross unresolved errors for the floating point >>> > > functions. Indeed, final linking step didn't include "-lm" to the >>> > > linker. >>> > > >>> > > Added it with commit 4e29da5cda6aa3, as found at: >>> > > http://members.hellug.gr/xrg/repos/psycopg2 >>> > > (browse at http://git.hellug.gr/?p=xrg/psycopg2) >>> > > >>> > > Please check your platforms. Is libm already linked against? Could you >>> > > forecast any side-effect from explicitly mentioning it (as in the patch) >>> > > ? >> > >> > On my Linux box libm is not linked in and I don't have any problem. Can >> > you please tell us you system version and the exact errors? >> > >> > federico > Do you use -Wl,no-undefined at the linker? My problem is at that step, and I > highly suspect that if I hadn't had that, the binary (psycopg.so) would still > run against the python binary (because python will load libm anyway). In fact compiling with --no-undefined throws a lot of errors. Can I ask you why you use it? If it is the correct thing to do we should add --no-undefined to all builds and pull in the right libraries. federico -- Federico Di Gregorio federico.digregorio@dndg.it Studio Associato Di Nunzio e Di Gregorio http://dndg.it In science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in poetry, it's the exact opposite. -- Paul Dirac
On Monday 14 March 2011, Federico Di Gregorio wrote: > On 14/03/11 13:59, P. Christeas wrote: > > Do you use -Wl,no-undefined at the linker? My problem is at that step, > > and I highly suspect that if I hadn't had that, the binary (psycopg.so) > > would still run against the python binary (because python will load libm > > anyway). > > In fact compiling with --no-undefined throws a lot of errors. Can I ask > you why you use it? If it is the correct thing to do we should add > --no-undefined to all builds and pull in the right libraries. > Found the reference: http://wiki.mandriva.com/en/Underlinking#ld_option_--no-undefined The paragraphs above that explain the rationale. I stick with their policy (carried over to Mageia, now) and wish that our build instructions fit that. -- Say NO to spam and viruses. Stop using Microsoft Windows!
On Mon, Mar 14, 2011 at 2:09 PM, Federico Di Gregorio <federico.digregorio@dndg.it> wrote: > In fact compiling with --no-undefined throws a lot of errors. Can I ask > you why you use it? If it is the correct thing to do we should add > --no-undefined to all builds and pull in the right libraries. "man floor(3)" says that link should be done with -lm, so I think it's probably just thanks to a tolerant linker that the problem has not emerged before (I don't know then if this level of tolerance is the least we can expect or if gcc is a very patient guy). Is it safe enough to add -lm to the linker flags for all the other distro? I think so - but I'm no authority on linking at all. I don't think instead we should be as strict as add --no-undefined: maybe having a mandriva builder in the build farm to check for regressions would be enough (it would be great if Christeas could provide it). -- Daniele
On 16/03/11 12:29, Daniele Varrazzo wrote: > On Mon, Mar 14, 2011 at 2:09 PM, Federico Di Gregorio > <federico.digregorio@dndg.it> wrote: > >> > In fact compiling with --no-undefined throws a lot of errors. Can I ask >> > you why you use it? If it is the correct thing to do we should add >> > --no-undefined to all builds and pull in the right libraries. > "man floor(3)" says that link should be done with -lm, so I think it's > probably just thanks to a tolerant linker that the problem has not > emerged before (I don't know then if this level of tolerance is the > least we can expect or if gcc is a very patient guy). > > Is it safe enough to add -lm to the linker flags for all the other > distro? I think so - but I'm no authority on linking at all. I don't > think instead we should be as strict as add --no-undefined: maybe > having a mandriva builder in the build farm to check for regressions > would be enough (it would be great if Christeas could provide it). At least on Debian (Ubuntu), RedHat and OpenSUSE should be fine. Adding --no-undefined also seems a good idea to catch future errors. federico -- Federico Di Gregorio federico.digregorio@dndg.it Studio Associato Di Nunzio e Di Gregorio http://dndg.it Those who do not study Lisp are doomed to reimplement it. Poorly. -- from Karl M. Hegbloom .signature